This invention relates to railway trailer hitches.
One currently used head design for railway trailer hitches includes a top plate having an opening into which a fixed jaw is inserted. The fixed jaw is a carbon steel forging. A movable jaw is supported for back and forth movement relative to the fixed jaw for locking the king pin of a trailer to the fifth wheel. The movable jaw is provided with movable extensions, and a lock screw mounted below the fifth wheel plate engages the extensions to move the movable jaw between open and closed positions.
A locking bar extending transversely of the head engages the extensions to maintain the movable jaw in closed position. See U.S. Pat. Nos. 3,145,000 and 3,964,766.
The fixed jaw forging has been subject to wear. When the fixed jaw has worn to the design limits, the jaw requires repair or replacement. To accomplish either repair or replacement is expensive. Moreover the car must be taken out of revenue service during the replacement period.
In another hitch head design, a pair of movable jaws are mounted below the top plate. A yoke engages the jaws and a stiff spring urges the yoke and the jaws into the closed position below a semi-circular top plate opening. See U.S. Pat. No. 3,225,707. In this arrangement the top plate has been subject to wear and cracking.